Expansion unit and apparatus for expanding tubular organ lumen

ABSTRACT

A tubular-organ expansion unit has a cylindrical body made of a shape memory alloy which is capable of maintaining the inside diameter of a tubular body organ. The tubular-organ expansion unit includes an X-ray contrast enhancer for improving the X-ray contrast of the tubular-organ expansion unit relative to the X-ray contrast of the tubular-organ expansion unit before the X-ray enhancer was provided on the expansion unit. In a tubular-organ expansion apparatus and a method for indwelling the tubular-organ expansion unit into a lumen of a tubular body organ, the shape memory alloy of the tubular-organ expansion unit will change its radial dimension in response to changes in temperature. The shape memory alloy may be bidirectional. The tubular-organ expansion apparatus not only includes the tubular-organ expansion unit but also comprises a catheter to which the tubular-body organ expansion unit is attached and a catheter sheath which can sheath the tubular body expansion unit and the portion of the catheter to which said unit is attached.

FIELD OF THE INVENTION

The present invention relates to an expansion unit for expanding thelumen of tubular organs, such as for example, a blood vessel, adigestive tube, an air tube, etc., and an apparatus for indwelling andwithdrawing the expansion unit.

BACKGROUND ART

Conventionally, expansion units (stents) have been proposed to maintainthe inside diameter of the luman of a tubular organ so as to prevent,for example, a coronary artery from relapsing into a constricted stateafter it has been dilated and indwelt by an angiectasia catheter.

A conventional expansion unit, as disclosed in Japanease Patent ExaminedPublication No. 61-6655, uses a unidirectional shape memory alloy madeof Ti-Ni binary alloys. A tube, previously having almost the same insidemeasurement as that of a normal blood vessel, is shaped before its shapeis memorized in the shape memory alloy. After the outside diameter ofthe shape memory alloy is reduced for easy introduction into a desiredlocation of a blood vessel, the alloy is heated in warm water and thelike to be expanded and recovered so as to return to the memorizedshape.

(A) For example, in the work of indwelling the above-describedconventional expansion unit into a desired location of the blood vessel,the expansion unit is attached to the distal end portion of a catheterand inserted to the desired location in a blood vessel using an X-raytransmission. It is therefore desirable to provide high contrast forX-rays when inserting and indwelling the expansion unit in the desiredlocation of tubular organs, such as a blood vessel.

However, the expansion unit is thinly built because of its inherentfunctions, such as maintaining the inside diameter of a blood vesselafter being indwelt in the blood vessel to keep a stable blood flow. Forwhich reason, poor contrast is provided for the unit.

Further, it is difficult to say from the viewpoint of material that ashape memory alloy, for instance, Ti-Ni binary alloy, comprising theexpansion unit provides high contrast.

(B) Also, in the work of indwelling the above-described conventionalexpansion unit made of the unidirectional shape memory alloy into adesired location in a blood vessel, as a normal practice, a guidingcatheter is first dwelt in the vessel and then the expansion unit slidedtoward a desired location, while simultaneously passing through theinside of the guiding catheter. In this case, however, since theexpansion unit slided through the narrow inside of the guiding catheterwithout a protective wrap around it, problems exist in that theexpansion unit may get caught or deformed midway through. Furthermore,because the guiding catheter is generally very rigid, it cannot travelthrough a bend in the periphery in the blood vessel. Therefore, when adesired location for indwelling is farther away from the bend, theexpansion unit may get caught and deformed midway through because theunit, without a protective wrap around it, together with the catheter,slides inside the vessel.

The expansion unit, which has already been proposed by the inventors ofthis invention, made of bidirectional shape memory alloy, isepoch-making as an expansion unit capable of changing indwellingpositions and withdrawal. That is, the expansion unit is characterizedin that a bidirectional shape memory alloy, in which two reversiblememory shapes, high and low temperature sides, appear reversibly on theborderline of a certain transformation point, is expanded diametricallyto obtain the inside measurement of a blood vessel and the like ataround body temperature, and is capable of travelling inside of theblood vessel by being contracted diametrically at or below bodytemperature. However, the above-described expansion unit slides throughthe narrow inside of the guiding catheter without a protective wraparound it. As a result, such problem exists in that the expansion unitmay get caught and deformed midway through. Moreover, while theexpansion unit slides inside of the guiding catheter, a large amount ofcooling water must be fed to keep the expansion unit contracteddiametrically. Further, as is the same with a unidirectional shapememory alloy, the guiding catheter is too rigid to travel through a bendof the periphery in a blood vessel. Therefore, when the expansion unitis inserted after the guiding catheter is removed or when a desiredlocation for indwelling is farther away from the bend, such problemsexist that the expansion unit may get caught and deformed midway turoughbecause the unit equipped with the catheter slides through the inside ofthe blood vessel without a protective wrap around it, and that a largeamount of cooling water must be fed to keep the expansion unitcontracted diametrically.

It is therefore an object of this invention to provide an expansion unitmade of a shape memory alloy, which allows high contrast for X-rays, toinsert and indwell the expansion unit into a desired location of atubular organ.

It is another object of this invention to make it possible for theexpansion unit to travel smoothly and readily through the tubular organ.

DISCLOSURE OF THE INVENTION

(A) The present invention is that a tubular-organ expansion unit havinga cylindrical body made of a shape memory alloy and capable ofmaintaining the inside diameter of the lumen of a tubular organ, ischaracterized in that a process has been conducted on at least a part ofthe boby for improving X-ray contrast.

Another feature of the present invention is that the cylindrical body iscoil-like.

Another feature of the present invention is that the cylindrical body isa helical shape in cross section.

Another feature of the present invention is that the cylindrical body isslit lengthwise.

Another feature of the present invention is that the cylindrical body ismesh-like.

Another feature of the present invention is that the cylindrical body isdefined by thin woven-shaped wires of shape memory alloy.

Another feature of the present invention is that the process includesplating of metals of a higher density than the shape memory alloy.

Another feature of the present invention is that the process meanswinding or pressing metals of a higher density than the shape memoryalloy.

An expansion unit made of shape memory alloy according to this inventionis expanded by 1 external force or 2 the effect of recovery in relationto memorized a shape based on temperature differences, to obtain theinside measurement of the luman of tubular organs after being insertedunder contrast of X-ray transmission into a desired location in tubularorgans such as a blood vessel.

Thus, the expansion unit provides high contrast for X-rays by plating orpressing at least part of the cylindrical body of the expansion unitwith metals whose density is higher than that of the shape memoryalloys. Accordingly, the expansion unit inserted into a tubular organprovides contrast for X-rays and is inserted and indwelt in the desiredlocation of the tubular organ.

As regards the shape memory alloy used for the expansion unit accordingto this invention, for example, Ti-Ni binary alloy (composition: Niatomic percent 50-53, preferably, 50-51, reverse transformation startingpoint: 30°-45° C.) is preferable.

Also, in this invention, such metals as Cu, Ag, Pt and Au whose densityis higher than that of the shape memory alloy used for increasing X-rayscontrast are preferable.

(B) The present invention is that the tubular-organ expansion apparatusfor indwelling the tubular-organ expansion unit in the lumen of atubular organ, is characterized in that the unit has a substantiallytubular body made of a shape memory alloy and capable of changing itsradial dimension in response to a change in temperature, the apparatuscomprises a catheter, where the tubular-organ expansion unit can beattached to the periphery of a unit-attaching portion in the vicinity ofthe distal end portion of the catheter, and a catheter sheath, with bothends thereof opened, into which the attached catheter with thetubular-organ expansion unit, can be sheathed.

Another feature of the present invention is that the catheter isprovided with a passageway extending from the base portion thereof to atleast a location in the vicinity of the distal end portion thereof, andside pores or slit-like communication apertures on the unit-attachingportion in the vicinity of the distal end portion thereof for providingcommunication between the passageway and the outside of the catheter.

Another feature of the present invention is that the outside diameter ofthe base portion and the distal end portion of the catheter, or theoutside diameter of the base of the catheter, are larger than that ofthe tubular-organ expansion unit attached to the unit-attaching portion.

Another feature of the present invention is that the catheter isprovided with the lumen of the catheter extending from the base portionthereof to at least a location in the vicinity of the distal end portionthereof, and a hollow hub on the base portion for communicating with thelumen of the catheter, the passageway being defined by the lumen of thecatheter and the lumen of the hub.

Another feature of the present invention is that the hub comprises abranch hub having two ports and one of the ports being provide with acheck valve.

Another feature of the present invention is that the catheter isprovided with at least one X-ray non-transmission marker in the vicinityof the distal portion thereof.

Another feature of the present invention is that an X-raynon-transmission material is mixed in the material of the cathetersheath, or the catheter sheath is provided with at least one X-raynon-transmission marker in the vicinity of the distal end portionthereof.

Another feature of the present invention is that the catheter sheath isconstructed with the lumen of the sheath extending to both distal endportions thereof and a hollow hub, having a check valve, at the basethereof for communicating with the lumen of the sheath.

The present invention is that the tubular-organ expansion apparatus forindwelling a tubular-organ expansion expansion unit in the lumen of atubular organ, is characterized in that the unit has a substantiallytubular body made of a shape memory alloy and capable of changing itsradial dimension in response to a change in temperature, the apparatuscomprises a catheter, whereby the tubular-organ expansion unit can beattached to the periphery of a unit-attaching portion in the vicinity ofthe distal end portion of the catheter, and a catheter sheath, whoseinside diameter is equal to or smaller than the outside diameter of thetubular-organ expansion unit, whereby with both ends of the cathetersheath opened, the attached contracted tubular-organ expansion unit, canbe sheathed.

Another feature of the present invention is that the catheter isprovided with a passageway extending from the base portion thereof to atleast a location in the vicinity of the distal end portion thereof, andside pores or slit-like communication apertures on the unit-attachingportion in the vicinity of the distal end portion thereof for providingcommunication between the passageway and the outside of the catheter.

Another feature of the present invention is that the catheter has thesame outside diameter as the unit-attaching portion in the vicinity ofthe distal end portion thereof, which is equal to or slightly largerthan the inside diameter of the tubular-organ expansion unit when theunit is contracted, and is capable of attaching the tubular-organexpansion unit to itself at substantially below body temperature.

Another feature of the present invention is that the catheter isprovided with the lumen of the catheter extending from the base portionthereof to at least a location in the vicinity of the distal end portionthereof, and a hollow hub on the base portion for communicating with thelumen of the catheter, the passageway being defined by the lumen of thecatheter and the lumen of the hub.

Another feature of the present invention is that the hub comprises abranch hub having two ports and one of the ports being provide with acheck valve.

Another feature of the present invention is that the outside diameter ofthe base portion and the distal end portion of the catheter, or theoutside diameter of the base portion of the catheter, are larger thanthat of the tubular-organ expansion unit attached to the unit-attachingportion.

Another feature of the present invention is that the catheter isprovided with at least one X-ray non-transmission marker in the vicinityof the distal end portion thereof.

Another feature of the present invention is that an X-raynon-transmission material is mixed in the material of the cathetersheath, or the catheter sheath is provided with at least one X-raynon-transmission marker in the vicinity of the distal end portionthereof.

Another feature of the present invention is that the catheter sheath isconstructed with the lumen of the sheath extending to both distal endportions thereof and a hollow hub, having a check valve, at the baseportion thereof for communicating with the lumen of the sheath.

(A system in which the expansion unit is made of a unidirectional shapememory alloy)

In the present invention, when the expansion unit is shaped by aunidirectional shape memory alloy, a substantially coil-like ormesh-like cylindrical expansion unit, having an outside diameter almostequal to or longer than the inside diameter of a tubular organ for theunit to be indwelt, which is memorized at around body temperature, isutilized.

Since the expansion unit may be deformed freely substantially below bodytemperature (transformation point), it is attached to the location inthe vicinity of the distal end portion of a catheter, while being woundaround the tip, so as to be sheathed in a catheter sheath. As describedabove, the expansion unit is readily indwelt in the desired location ofthe tubular organ directly or with the aid of the guiding catheter bymeans of the combination of the catheter and the catheter sheath intothe tubular organ.

Namely, a guide wire is inserted by a known technique into the tubularorgan where the expansion unit is to rest, and then, along the guidewire, the expansion unit is readily inserted into the disired locationby using, directly or with the aid of the guiding catheter, thecombination of the catheter and the catheter sheath into the tubularorgan. At this stage, according to this invention, because of thecatheter sheath, the expansion unit is not directly exposed to theguiding catheter or the tubular organ so that the unit does not getcaught or deformed midway through. Furthermore, because the cathetersheath is flexible, it can easily slide, along with the expansion unitand the catheter, through the bend of a blood vessel.

The expansion unit inserted according to the above-described isprojected out of the catheter sheath, with the unit attached to thecatheter, before being expanded by the heat of body temperature andindwelt in the desired location of the tubular organ.

While the expansion unit made of the aforementioned unidirectional shapememory alloy is inserted, cooling water may be fed from the cathetersheath and/or the catheter and while it is indwelt, warm water may befed from the catheter sheath and/or the catheter. In a preferredembodiment in accordance with this invention, the catheter is providedwith a passageway extending from its base portion to at least thelocation close to its end and with a communication apertures to connectthe passageway to the end surface where the expansion unit is to beattached. From the communication apertures the cooling water and thewarm water are fed.

In this invention, the unidirectional shape memory alloy means an alloywhere a thermal plasticity type martensite transformation is developedso that the alloy is changed to the previously memorized shaped of amatrix at the reverse transformation baginning point or over. The abovealloy may also be deformed freely at or under the transformation point,and once it recovers, the memorized shape at the reverse transformationpoint or over, it maintains the memorized shape, even at or under thereverse transformation point, unless an external force is applied.

(A system in which the expansion unit is made of a bidirectional shapememory alloy)

In the present invention, when the expansion unit is shaped by abidirectional shape memory alloy, a substantially coil-like or mesh-likecylindrical expansion unit, having an outside diameter, almost equal toor shorter than the lumen of a tubular organ for the unit to be indwelt,which is memorized substantially below body temperature, is utilized. Inthe expansion unit made of the bidirectional shape memory alloy, theoutside diameter, which is substantially equal to or somewhat longerthan the inside diameter of a tubular organ for the unit to be expandedand indwelt at around body temperature, is memorized. While theexpansion unit is attached to the catheter, the unit is sheathed into acatheter sheath. The expansion unit is readily indwelt in and withdrawnfrom the desired location of the tubular organ directly or with the aidof the guiding catheter by means of the combination of the catheter andthe catheter sheath into the tubular organ.

That is, a guide wire is inserted by a known technique into the tubularorgan where the expansion unit is to rest, and then, along the guidewire, the expansion unit is readily inserted into the desired locationof the tubular organ directly or with the aid of the guiding catheter bymeans of the combination of the catheter and the catheter sheath intothe tubular organ. According to this invention, at this stage, becauseof the catheter sheath, the expansion unit, while it is being attachedto the catheter, is firmly maintained in the sheath. Therefore, a largeamount of cooling water is not required for winding the expansion unitaround the catheter tightly so as to keep the inside diametercontracted. A patient's discomfort is thus reduced. Because of thecatheter sheath, the expansion unit is not directly exposed to theguiding catheter or the tubular organ so that the unit does not getcaught or deformed midway through. Furthermore, because the cathetersheath is flexible, it can easily slide, along with the expansion unitand the catheter, through the bend of a blood vessel.

The expansion unit inserted according to the above-described procedureis supplied with cooling water from the catheter sheath and/or thecatheter to be wound around the catheter. Under this condition, afterthe unit is projected out of the catheter sheath, the supply of thecooling water is stopped. As a result, the expansion unit is heated andexpanded by body temperature, and indwelt in the desired location.

Moreover, the withdrawal of the expansion unit thus indwelt in thedesired location is performed according to the following procedures. Theguide wire is first passed the location where the expansion unit isindwelt and along with this wire, the catheter, together with thecatheter sheath, is inserted into the indwelling location. The distalend portion of the catheter is then projected out of the cathetersheath. The cooling water is fed from the catheter and/or cathetersheath for winding the expansion unit around the location where the unitis to be attached so as to contract the inside diameter of the unit. Thewound expansion unit is withdrawn together with the catheter into thecatheter sheath. In this case, a small amount of cooling water issufficient. Further, once the expansion unit is pulled into the cathetersheath, it is certainly withdrawn without being caught or deformedmidway through.

In a preferred embodiment in accordance with this invention, thecatheter is provided with a passageway extending from its base portionto at least the location in the vicinity of the distal end portion andwith communication apertures, which connect the passageway and thesurface of the end where the expansion unit is to be attached. When theexpansion unit, made of the above-described bidirectional shape memoryalloy, is inserted or withdrawn, the cooling water may be fed from thecommunication apertures.

In this invention, the bidirectional shape memory alloy means the alloywhere previously memorized shapes at high and low temperatures on theborderline of a certain transformation point appear reversibly accordingto changes in temperature.

As regards shape memory alloy used for the expansion unit according tothis invention, for example, Ti-Ni binary alloy (composition: Ni atomicpercent 50-53, preferably, 50-51, transformation starting point: As30°-45° C., Ms: 10°-30° C.) is preferable.

(C) The present invention is that the method of medically treating thelumen of a tubular organ by indwelling a tubular-organ expansion unit,is defined substantially cylindrically by a shape memory alloy whichchanges diametrically in size in response to a change in temperature,into the lumen of the tubular organ, wherein said tubular-organexpansion unit is attached to the periphery of a unit-attaching portionarranged in the vicinity of the distal end portion of the catheter, andafter the combination of the catheter with the attached tubular-organexpansion unit and the catheter sheath having both ends opened, intowhich the catheter is sheathed, is inserted into a desired location ofthe tubular organ, the catheter and the tubular-organ expansion unit areprojected out of the catheter sheath and the tubular-organ expansionunit is expanded by heat of the body for indwelling into the desiredlocation.

Another feature of the present invention is that the method of medicallytreating the lumen of a tubular organ by indwelling a tubular-organexpansion unit, is defined substantially cylindrically by abidirectional shape memory alloy which changes diametrically in size inresponse to a change in temperature, into the lumen of the tubularorgan, wherein the tubular-organ expansion unit is attached to theperiphery of a unit-attaching portion arranged in the vicinity of thedistal end portion of a catheter, and after the combination of thecatheter with the attached tubular-organ expansion unit and the cathetersheath having both ends opened, into which the catheter is sheathed, isinserted into a desired location of the tubular organ, the catheter andthe tubular-organ expansion unit are projected out of the cathetersheath and the tubular-organ expansion unit is expanded by heat of thebody for indwelling into the desired location.

Another feature of the present invention is that the medical treatmentmethod is characterized in that after the combination of the catheterand the catheter sheath is inserted into a location where thetubular-organ expansion unit is to be indwelt, the distal end portion ofthe catheter is projected out of the catheter sheath, the tubular-organexpansion unit then being reduced in size by the feeding of coolingwater from the catheter sheath and/or the catheter in order to be woundaround the unit-attaching portion of said catheter, and the woundtubular-organ expansion unit, together with the catheter, is withdrawninside the catheter sheath.

Another feature of the present invention is that the method of medicallytreating the lumen of a tubular organ by indwelling a tubular-organexpansion unit, is defined substantially cylindrically by a shape memoryalloy which changes diametrically in size in response to a change intemperature, into the lumen of the tubular oragan, wherein thetubular-organ expansion unit is attached to the periphery of aunit-attaching portion arranged in the vicinity of the distal endportion of a catheter, and after the combination of the catheter withthe attached tubular-organ expansion unit and the catheter sheath havingboth ends opened, into which the catheter is sheathed, is inserted,through the lumen of a guiding catheter already indwelt in the tubularorgan, into a desired location of the tubular organ, the catheter andthe tubular-organ expansion unit are projected out of the cathetersheath and the tubular-organ expansion unit is expanded by heat of thebody for indwelling into the desired location.

Another feature of the present invention is that the method of medicallytreating the lumen of a tubular organ by indwelling a tubular-organexpansion unit, is defined substantially cylindrically by a shape memoryalloy which changes diametrically in size in response to a change intemperature, into the lumen of the tubular organ, wherein thetubular-organ expansion unit is attached to the periphery of aunit-attaching portion arranged in the vicinity of the distal endportion of a catheter, and after the combination of the catheter withthe attached tubular-organ expansion unit and the catheter sheath havingboth ends opened, into which the catheter is sheathed, is inserted,through the lumen of a guiding catheter already indwelt in the tubularorgan, into a desired location of the tubular organ, the catheter andthe tubular-organ expansion unit are projected out of the cathetersheath and the tubular-organ expansion unit is expanded by heat of thebody for indwelling into the desired location.

Another feature of the present invention is that the medical treatmentmethod is characterized in that after the combination of the catheterand the catheter sheath is, through the lumen of a guiding catheteralready indwelt in the tubular organ, inserted into a location where thetubular-organ expansion unit is to be indwelt, the distal end portion ofthe catheter is projected out of the catheter sheath, the tubular-organexpansion unit then being reduced in size by the feeding of coolingwater from the catheter sheath and/or the catheter in order to be woundaround th unit-attaching portion of the catheter, and the woundtubular-organ expansion unit, together with the catheter, is withdrawninside the catheter sheath.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(A), (B) is a side view showing an expansion unit of a firstembodiment according to the present invention;

FIG. 2 is a cross-sectional view illustrating an indwelling catheter;

FIG. 3 is a cross-sectional view illustrating a withdrawing catheter;

FIG. 4(A) is a schematic illustration showing the expansion unit whileit is being inserted;

FIG. 4(B) is a schematic illustration showing the expansion unit whileit is indwelt;

FIG. 4(C) is a schematic illustration showing the expansion unit whileit is being withdrawn;

FIG. 5(A), (B) is a perspective view showing the expansion unit of asecond embodiment in accordance with this invention;

FIG. 6(A), (B) is a perspective view depicting the expansion unit of athird embodiment according to this invention;

FIG. 7(A), (B) is a perspective view illustrating the expansion unit ofa fourth embodiment according to this invention;

FIG. 8 is a cross-sectional view showing an expansion system of a fifthembodiment according to this invention;

FIG. 9(A), (B) is a side view showing the expansion unit;

FIG. 10 is a side view illustrating a catheter;

FIG. 11 is a side view showing a catheter sheath;

FIG. 12(A) to (E) is a schematic illustration showing the expansion unitin processes of inserting and withdrawing; and

FIG. 13 is a schematic illustration showing the expansion unit inanother process of inserting and withdrawing.

THE BEST MODE FOR CARRYING OUT THE INVENTION FIRST EMBODIMENT

An expansion unit 10 (hereinafter referred to as a stent) issubstantially cylindrically (coil-like in this embodiment) formed by aunidirectional shape memory alloy which changes the size diametricallyin accordance with changes in temperature. The measurement of the stent10 in its matrix is set to a smaller size than that of a tubular organ,in this embodiment a blood vessel 11 (Refer to FIG. 1(A)). Also, in thisembodiment, the reverse transformation starting point for the shapememory alloy comprising the stent 10 is set at a temperature above bodytemperature in order to change the stent 10 diametrically after thepoint exceeds the body temperature. The stent 10 is further expandeddiametrically by an external force (Refer to FIG. 1(B)). In thisinvention, a unidirectional shape memory alloy means the alloy, in whicha thermal plasticity type martensite transformation is developed so thatthe alloy is changed to the previously memorized shaped of a matrix ator over the reverse transformation beginning point. The above alloy mayalso be deformed freely at or under the transformation point, and onceit recovers the memorized shape at or over the reverse transformationpoint, it maintains the memorized shape, even at or under the reversetransformation point, unless an external force is applied.

The distal end portion of the cylindrical stent 10 is a high contrastportion 10a. The high contrast portion 10a is formed by the plating orpressing metals with a higher density (for example, Cu, Ag, Pt and Au)than the shape memory alloy comprising the stent 10. The high contrastportion may be at the rear end of, or at the center of, or at any twopoints of the stent 10, or the whole body of the cylindrical stent 10.

As shown in FIG. 2, for example, an indwelling catheter 20, is used forindwelling the above mentioned stent 10 into a desired location of atubular organ. The indwelling catheter 20 is provided with a balloon 21at its distal end and is guided by a guide wire (28 of FIG. 4(A), (B)),which is inserted to a main passageway 22, toward the desired locationof the tubular organ. The balloon 21 is expanded by a balloon swellingliquid fed from a subpassageway for liquid injection 23 so as to providethe reduced-diameter stent 10 already attached around the balloon withan external force. A hub of the main passageway 22 is provided with acheck valve 24 to prevent blood leakage and the like caused by thepassing of the guide wire. Numeral 25 indicates an insufflator, and 27an outlet subpassageway communicating with the inside space of theballoon 21. The outlet subpassageway 27 is provided with a three-waycock 26 at its base.

Further, as shown in FIG. 3 for instance, a withdrawing catheter 30 isused for withdrawing (or changing an indwelling location) after theaforementioned stent 10 is indwelt. The withdrawing catheter 30 isprovided with side pores 31 on its distal end and guided by a guide wire(37 of FIG. 4(C) to the location in the tubular organ where the stent isto rest. A stent heating liquid, fed from a subpassageway for liquidinjection 33 into a main passageway 32, flows out of the side pores 31so at to heat the expanded stent located around the side pores 31 up toover the reverse transformation starting point or over. Consequently,the memory shape in the matrix of the stent is recovered or reduced inits size. A hub of the main passageway 32 is provided with a check valve34 to prevent blood leakage and the like caused by the passing of theguide wire. A boss of a subpassageway 33 is provided with a three-waycock 26 to inject the stent heating liquid.

The effect of the above-described stent 10 will now be described.

According to the stent 10 described above, at or under thetransformation point of the shape memory allow, the stent 10 is reducedto a size smaller than the inside measurement of the blood vessel. Asshown in FIG. 4(A), the balloon 21 is attached to the distal end portionof the indwelling catheter 20 and inserted into the desired location ofthe blood vessel 11 under an X-ray contrast, and then, as shown in FIG.4(B), the stent 10 is expanded in size by the external force caused bythe swelling of the balloon 21 so that the stent 10 is indwelt, thusobtaining the inside diameter of the blood vessel 11.

As shown in FIG. 4(C), when the stent described above is withdrawn, orwhen the indwelling location of the stent is changed, the withdrawingcatheter 30, with the side pores 31 at its distal end portion, isinserted into the location where the stent 10 is indwelt. A liquid,having the reverse transformation starting point or over for the shapememory alloy, flows out of the side pores 31 and causes the stent 10 toexceed the reverse transformation starting point for returning to theonce memorized shape or for making the diameter of the stent smallerthan the inside diameter of the blood vessel 11. Thus the stent 10 cantravel along with the withdrawing catheter 30, just like while beingwound around the distal end portion of the withdrawing catheter 30.

That is, even after the catheter 10 is expanded in the blood vessel 11,it can be freely reduced in size. For which reason, it is possible towithdraw it from the indwelling location and change locations.

Further, the stent 10 is provided with the high contrast portion 10aformed by plating or pressing higher density metals than the shapememory alloy with at least a part of the stent 10, thereby providinghigh contrast. Thus, the stent 10 inserted into the inside of the bloodvessel 11 definitely provides contrast under X-ray and can be indweltinto a desired location.

As regards the shape memory properties in accordance with the presentinvention, in addition to the properties for the stent 10 describedabove, other properties as follows are acceptable: a bidirectional shapememory alloy, in which two reversible memory shapes, i.e., high and lowtemperature sides, appear reversibly on the borderline of a certaintransformation point, which is expanded diametrically to obtain theinside diameter of a blood vessel and the like at around bodytemperature, and which is capable of travelling inside of the bloodvessel by being contracted diametrically at or below body temperature.

As regards the shape of the stent 10 according to this invention, otherthan the coil-like stent 10 of the first embodiment, substantiallycylindrical things are included. "Substantially cylindrical things" inthis invention mean things which have a surface contacting with at leastpart of a lumen for expanding and maintaining the lumen of a tubularorgan.

SECOND EMBODIMENT

A stent 40, according to a second embodiment, is constructed in aherical shape in cross section so as to contract (FIG. 5(A)), or expand(FIG. 5(B)). Numeral 40a indicates a high contrast portion.

THIRD EMBODIMENT

A stent 50, with a longitudinal slit, according to a third embodiment,is cylindrically constructed so as to contract (FIG. 6(A)) or expand(FIG. 6(B)). Numeral 50a indicates a high contrast portion.

FOURTH EMBODIMENT

A stent 60, according to a fourth embodiment, is constructed in amesh-like manner so as to contract (FIG. 6 (A)), or expand (FIG. 6(B)).It is desirable that the distal end portion of the mesh be fixed bymeans of welding or an adhesive so that the thin wires of the shapememory alloy do not come loose. It is further desirable that theintersections comprising the thin wires of the alloy be fixed by meansof welding or an adhesive. Numeral 60a indicates a high contrastportion.

The effects of the embodiments in accordance with this invention willnow be specifically described.

The same shape stent, as shown in FIG. 1(A), (B), made of Ti-Ni binaryallow (including atomic percent approximately 51), with a wall thicknessof 0.004 mm, a width of 1 mm, is washed off with water after anelectrolytic degreasing and an acid treatment, and plated with Au in thesolution of KAu(CN)₂. When the already plated stent, and another stentnot yet plated, are contrasted by X-rays under the same condition, theplated stent proves to provide improved contrast.

For proof of the improvement in contrast of the Au plating, the stentwith Au plating and the stent not yet plated are exposed by X-rays underthe condition of 45 kV and 2.0 mA, and a contrast picture is obtained.The absorbance of 600 nm of the picture is then obtained by a Shimazusecond wavelength chromato scanner made by Shimazu Corp. In the spectrumthus obtained, let the contrast of the complete transmission of X-raysbe 0, and the section where plating is not yet performed 1, then the Auplated stent becomes 3. A remarkable improvement in contrast by Auplating is proved.

FIG. 8 is a cross-sectional view showing an expansion system of a fifthembodiment according to this invention;

FIG. 9(A), (B) is a side view showing the expansion unit;

FIG. 10 is a side view illustrating a catheter;

FIG. 11 is a side view showing a catheter sheath; and

FIG. 12(A) to (E) is a schematic illustration showing the expansion unitin processes of inserting and withdrawing.

FIFTH EMBODIMENT

An expansion system 101 is constructed in a combination of the expansionunit (stent) 110, the catheter 120 and the catheter sheath 130.

As shown in FIG. 9(A), (B), the stent 110 is molded substantially, in acylindrical and spiral manner, by a thin wire of a flat bidirectionalshape memory alloy (made of, for example, Ni-Ti binary, Cu-Al-Niternary, Cu-Zn-Al ternary). The stent 10 is kept expanded diametricallyin its shape or at around body temperature (for example, 30°-35° C.)(FIG. 9(B), and is contracted diametrically in its shape substantiallybelow body temperature (for example, 15°-25° C.) (FIG. 9(A)). In thestent (Ti-Ni binary bidirectional shape memory allow: Ni atomic percentabout 51, a wall thickness of 0.03 mm, a width of 1 mm), the insidemeasurement thereof changes to φ1.6 mm at or under 20° C., and to φ2.8mm at or over 32° C.

The inside diameter, length, etc. of the stent 110 may be appropriatelydetermined by the inside diameter and the length of a tubular organwhere the stent is to rest. That is, the inside diameter of the stent110 is made equal to that of the tubular organ, such as a blood vessel,for the stent is to rest, when it is expanded, and is made small enoughfor the stent to be guided to a location where the stent is indwelt.

In this embodiment, the shape of the stent is not limited to the spiralshape described, but may be substantially cylindrically formed, such asfor example, in a mesh-like or a herical shape.

Furthermore, it is desirable that the stent 110 be provided with anX-ray non-transmission marker 111 on at least part of the cylindricalbody thereof.

The catheter 120 comprises a catheter tube 121 (made of thermoplasticresins, such as polyethylene, EVA or PVC) and a hollow hub 122 (made of,for example, polycarbonate or polyethylene) at the base of the cathetertube 121 to communicate with a lumen extending from the base of thecatheter tube 121 to the distal end portion thereof. The catheter 120allows the provision of the above-mentioned stent 110 on the peripheryof a stent-attaching portion 123 close to the distal end portion of thecatheter tube 121.

The catheter 120 also provides a passageway 124 between the lumen in thecatheter tube 121 and the inside of the hub 122. The stent-attachingportion 123 of the catheter tube 121 is provided with a large number ofside pores-like communication apertures 125 for communicating betweenthe passageway 124 and the outside. The stent cooling water fed to thepassageway 124 is discharged radiately from the communication apertures125. The communication apertures may also be slit-like.

It is further desirable that the stent 120 be provided with an expansion126, on the base portion of the stent-attaching portion 123 where thecommunication apertures 125 are located, and which has an outsidemeasurement larger than that of the stent 110 attached to thestent-attaching portion 123. The reason for the above arrangement isthat when the stent 110 is withdrawn, it is pulled inside the cathetersheath 130 while being wound around the stent-attaching portion 123.This prevents the catheter from being caught at the distal end portionof the catheter sheath 130. The expansion 126 may be arranged on boththe base side and the distal end portion side of the stent attachingportion 123.

Moreover, it is desirable that the catheter 120 be provided with anX-ray non-transmission marker 127 (made of, for instance, gold orplatinum) at a location in the vicinity of the distal end portion of thecatheter tube 121. The marker permits confirmation of the location ofthe catheter 120 under x-ray fluoroscopy and the relative locations ofthe stent 110 and the sheath 130.

As shown in FIG. 10, the hub 122 of the catheter 120 comprises a linearcylindrical body 122A and a branch 122B branched at the center of thebody 122A. The linear cylindrical body 122A serves as an entrance forthe guide wire. A check valve 128 (made of a flexible material, such assilicone rubber) is arranged close to the opening of the base of thebody to prevent blood leakage and the like caused by the guide wire. Thebranch 122B, equipped with a three-way cock 129, is utilized forintroducing cooling water and the like.

The catheter sheath 130 comprises a catheter tube 121, with both distalend portions opened, (made of, for example, PVC, polyethylene andfluorocarbon resin) and a hollow sheath hub 132 (made of, for example,polycarbonate or polyethylene) at the base of a catheter tube 121 tocommunicate with the lumen of the sheath tube 131. The catheter 120 withthe stent 110 attached may be attached on the lumen of the cathetersheath 130.

The catheter sheath 130 must be flexible to travel through any bends inthe periphery of a blood vessel, with the stent 110 and the catheter 120sheathed into it. For this purpose, as the sheath 130 may be made ofpolyvinyl chloride, 15-40 parts by weight, preferably 20-30 ofdiethylhexylphthalate (DEHP) in a plasticizer are desirably containedfor 100 parts by weight of polyvinyl chloride.

The catheter sheath 130 may desirably include the catheter tube 131, inwhose material an X-ray contrast medium is so mixed as to confirm thelocation of each component under X-ray transmission. The catheter sheath130 may also be provided with at least one X-ray non-transmission markerin the vicinity of the distal end portion of the sheath tube 131.

It is also desirable that the inside diameter of the sheath tube 131 ofthe catheter sheath 130 be smaller than that of the diameter of thestent 110 when it is expanded. This is because when the stent 110 isinserted by means of a combination of the stent 110, the catheter 120and the sheath 130, the stent 110 is fixed to the inside of the sheath130 due to the fact that the stent 110 tends to expand to a size largerthan the inside diameter of the sheath. For the above-described reason,when the stent 110 is inserted by means of the combination of the stent110, the catheter 120 and the sheath 130, into a location close to theindwelling location, the cooling water must not flow to wind the stent110 around the catheter 120. Thus, firm insertion of the stent isachieved. A patient's discomfort will be greatly reduced by a smallamount of the cooling water required.

A sheath hub 132 of the catheter sheath 130 is provided with a checkvalve 133 for preventing blood from being leaked by the passing of thecatheter 120 through the boss. The sheath hub 132 is further providedwith a sheath port 134 for injection of a contrast medium and the like.

The effect of the above-mentioned embodiment will now be described.

The expansion system 101 hitherto described comprises the stent 110 madeof the bidirectional shape memory alloy, where the outside diameter ofthe stent, smaller than the inside diameter of the lumen of the tubularorgan within which the stent is to rest, is memorized when thetemperature in the system is substantially below body temperature.Moreover, the stent 110 expands at around body temperature, andmemorizes its outside diameter, equal to or somewhat larger than theinside diameter of the lumen of the tubular organ where the stent is torest. The stent 110 is sheathed into the catheter sheath 130, while itis attached to the catheter 120. The stent 110 is readily indwelt in andwithdrawn from a desired location of the tubular organ by inserting theabove combination into the location.

That is, a guide wire is inserted by a known technique into the tubularorgan where the stent is to rest, then, along the guide wire, the stent110 is readily inserted into the desired location by using the abovecombination (Refer to FIG. 12(A)).

As shown in FIG. 12(A), instead of introducing directly a combination ofthe stent 110, the catheter 120 and the catheter sheath 130 into thetubular organ 11, it may be acceptable that, as shown in FIG. 13, theabove combination is first introduced to the inside of the guidingcatheter 200, which is already indwelt in the tubular organ 11, and theninserted into the tubular organ 11. At this stage, the guiding catheter200 encounters the problem that it can hardly pass through a bend in theperiphery of the blood vessel because of its relative stiffness. Thismeans that it is difficult for the guiding catheter 200 to be indweltbeforehand in the desired location of the tubular organ 11. Therefore,when the desired location is farther away from the indwelling locationof the guiding catheter 200, the combination of the stent 110, thecatheter 120 and the catheter sheath 130 is directly inserted into thetubular organ 11, after the combination passes the end of the locationwhere the guiding catheter is indwelt.

According to this invention, at this time, since the stent 110 is firmlymaintained within the catheter 120 thanks to the catheter sheath 130,while it is attached to the catheter 120, a large amount of coolingwater must not be fed to keep the stent reduced in size, as when windingthe stent around the catheter 120 tightly. This will reduce thepatient's discomfort. Moreover, because of the catheter sheath 130, thestent 110 is not directly exposed to the guiding catheter 200 or thetubular organ 11, and is prevented from being caught or deformed midwaythrough.

The stent 110 thus inserted into the desired location is projected outof the catheter sheath 130 (FIG. 12(C)), while it is wound around thecatheter 120 (FIG. 12(B)) by the cooling water red from the cathetersheath 130 and/or the communication apertures 125 of the catheter 120.After the stent 110 is thus projected (FIG. 12(C)), the supply of thecooling water is stopped. The stent 110 is heated by body temperature,and is expanded (FIG. 12(D)) to indwell in the desired location of thetubular organ (FIG. 12(E)).

Further, for withdrawing the stent thus indwelt in the desired location,the guide wire is passed the location where the stent 110 is indwelt,and along the guide wire, the combination of the catheter 120 and thecatheter sheath 130 is inserted into the location. The diatal endportion of the catheter 120 is then projected out of the catheter sheath130. The stent 110 is reduced in size by the cooling water fed from thecatheter sheath 130 and/or the communication apertures 125 of thecatheter 120 and is wound around the catheter attaching portion of thecatheter 120. The wound stent 110 can be withdrawn by being pulled intothe catheter sheath 130 together with the catheter 120. In this casetoo, only a small amount of the cooling water is required. The stent 110after being pulled into the catheter sheath 130 can be definitelywithdrawn without being caught or deformed midway through.

In an embodiment according to this invention, when an expansion unit isformed by a unidirectional shape memory alloy, a coil-like or mesh-like,substantially cylindrical expansion unit is utilized. The unit memorizesoutside diameter, equal to or somewhat larger than the inside diameterof a tubular organ where the unit is to rest at around body temperature.

Since the expansion unit can be changed freely in size at temperature(at or under the transformation point) substantially below bodytemperature, it is sheathed by the catheter sheath while it is woundaround the a unit-attaching portion in the vicinity of the distal endportion of the catheter. The expansion unit is readily indwelt byinserting the combination of the expansion unit attached to the catheterand the sheath, into which the catheter is sheathed.

Namely, the guide wire is inserted by a known technique into the tubularorgan where the expansion unit is to rest, and then, along the guidewire, the unit is readily inserted into the desired location by usingthe above combination. At this stage, in this invention, because of thecatheter sheath, the expansion unit is not directly exposed to thetubular organ, and is prevented from being caught or deformed midwaythrough.

After the expansion unit thus inserted into the desired location isprojected out of the catheter sheath, while it is attached to thecatheter, the unit is expanded in size by the heat of the bodytemperature so as to rest in the direction location of the tubularorgan.

When the expansion unit, made of the above-described unidirectionalshape memory alloy, is inserted, the cooling water may be fed from thecatheter sheath, and when the unit is indwelt, warm water from thecatheter sheath. Furthermore, in a preferred embodiment according to thepresent invention, the catheter can be provided with a passagewayextending from its base to a location at least as far as the vicinity ofthe distal end portion and the communication apertures, through whichthe cooling and the warm water may be fed, for communicating thepassageway with the surface of the unit-attaching portion in thevicinity of its distal end portion.

The effects of the embodiments according to this invention will now bespecifically described.

EXAMPLE 1

A stent made of bidirectional shape memory alloy was indwelt andwithdrawn, using the following materials.

The material of the stent was Ti-Ni binary alloy (approximately 51percent Ni atoms), and the shape of the stent (wall thickness: t=0.03mm, width: w=1 mm) was formed into a spiral, as shown in FIG. 2. Thestent was changed in its diameter, to φ1.6 mm at or under 20° C., and toφ2.8 mm at or over 32° C. Two gold markers (wall thickness t=0.02 mm,w=1.0 mm) were fixed to the both ends of the stent.

The material of the catheter was a blend of polyethylene and EVA, andthe shape of the catheter was as shown in FIG. 3.

The material composition of the catheter sheath was 100 parts by weightof polyvinyl chloride, 50 parts by weight of Bi₂ O₃ and 26 parts byweight of diethylhexylphthalate, and the shape of the sheath (outsidediameter 3.0 mm, inside diameter 2.6 mm and wall thichness 0.2 mm) wasas shown in FIG. 4.

The stent was indwelt and withdrawn in accordance with the followingprocedures.

1 80 mg of aspirin and 50 mg of dipyridamole were orally administered toa mongrel dog (17 kg) one day prior to an operation and again on the dayof the operation.

2 Under general anesthesia, the dog was heparinized (200 U/kg) after anintroducer was indwelt by a know technique in an arteria femoralis.

3 A replacing guide wire was inserted by a known technique into a chosenblood vessel. A right arteria cervicalis superficialis was chosen inthis case.

4 The combination of the stent, the catheter and the sheath (Refer toFIG. 1) was inserted, along the guide wire, into a location just beforethe indwelling location.

5 30 ml per minute of the cooling water (ice-cooled physiological saltsolution) was fed from the catheter side pores (communication apertures)to contract the stent.

6 The catheter was pushed out of the sheath to move it to the locationwhere the catheter was to be indwelt. The feeding of the cooling waterwas stopped to expand and indwell the stent, and then the cathetersheath was withdrawn.

7 Thirty minutes later, along the guide wire, the combination of thecatheter and the sheath was inserted into a location just before theindwelling location and then the catheter alone was inserted fartherinto the indwelling location, followed by the feeding of the coolingwater.

8 After it was confirmed that the stent was wound around the catheter,the catheter together with the stent was pulled into the sheath. Thefeeding of the cooling water was then stopped and the stent togetherwith the sheath was pulled out of the dog's body, thus completing thewithdrawal operation.

The above procedures, from 3 to 8, were performed by using X-raytransmission.

By the above-mentioned procedures, it has been proved that indwellingand withdrawing of the stent can be easily performed.

EXAMPLE 2

A stent made of the unidirectional shape memory alloy was easily indweltby the following devices and procedures.

The stent had the same measurements and composition as the firstembodiment. A 2.8 mm shape with a temperature at or over 42° C. wasmemorized.

The same catheter and catheter sheath as in the first example was used.

1 In the same way as in the first example, the guide wire was indwelt inthe right arteria cervical is superficialis of a mongrel dog, the abovestent, together with the sheath, while the stent was wound around thecatheter, being inserted into the indwelling location along the guidewire.

2 The catheter and the stent were projected out at the indwellinglocation, and physiological salt solution heated up to 45° C. wasinjected from the catheter side pores. The stent was thus expanded andindwelt.

EXAMPLE 3

Before a stent, which had the same composition as the first example,with a spiral shape (wall thickness: t=0.015 mm, width: w=1.0 mm), asshown in FIG. 2, and a diameter changed to φ1.4 mm with a temperature ator under 20° C., and to φ2.8 mm with a temperature at or over 32° C.,was inserted or withdrawn, a guiding catheter was indwelt. The abovecombination was guided by the guiding catheter.

The material of the guiding catheter was made of polyurethane, and theoutside diameter of the catheter was φ3.0 mm and the inside diameterφ2.4 mm.

The material of the catheter sheath was the same as in the firstembodiment, and the outside diameter of the sheath was φ2.0 mm and theinside diameter φ1.8 mm.

The material of the catheter was a blend of polyethylene and EVA, andthe shape was as shown in FIG. 3.

The combination of the guiding catheter, the stent, the catheter and thecatheter sheath was firmly guided by the guiding catheter to a point inthe blood vessel which was midway to the desired location. Thecombination was directly inserted into the blood vessel after travellingthrough the end where the guiding catheter was indwelt. As a result, itwas proved that the stent could be easily indwelt and withdrawn.

INDUSTRIAL APPLICABILITY

An expansion unit according to the present invention is utilized formaintaining the inside measurements of the lumen of such tubular organas, for example, a blood vessel, a digestive tube or an air tube so asto prevent a coronary artery from relapsing into a constricted stateafter it has been dilated and indwelt by an angiectasia catheter.

An apparatus according to this invention is used for indwelling andwithdrawing the aforementioned expansion unit.

We claim:
 1. A tubular-organ expansion unit comprising:a mesh-likecylindrical body comprising a plurality of thin-woven wires that areformed of a shape memory alloy which is insertable into a tubular bodyorgan and which is capable of maintaining an inside diameter of a lumenof the tubular body organ, said cylindrical body having a given X-raycontrast; and X-ray contrast enhancing means on at least a portion ofsaid cylindrical body for improving the X-ray contrast of at least saidportion of said cylindrical body relative to said given X-ray contrast.2. A tubular-organ expansion unit according to claim 1, wherein thecylindrical body comprises a coil-like member.
 3. A tubular-organexpansion unit according to claim 1, wherein said cylindrical body has ahelical shape.
 4. A tubular-organ expansion unit according to claim 1,wherein said cylindrical body has a longitudinal axis, and wherein saidcylindrical body includes a slit formed substantially parallel to thelongitudinal axis.
 5. A tubular-organ expansion unit according to claim1, wherein:the shape memory alloy has a given density; and the X-raycontrast enhancing means comprises a metal plated on said cylindricalbody, said metal having a density higher then the given density of saidshape memory alloy.
 6. A tubular-organ expansion unit according to claim1, wherein:the shape memory alloy has a given density; and saidcylindrical body has a metal pressed thereon, said metal having a higherdensity than said given density of said shape memory alloy.
 7. Atubular-organ expansion unit according to claim 1, wherein:the shapememory alloy has a given density; and said cylindrical body has a metalwound thereon having a higher density than said given density of saidshape memory alloy.
 8. A tubular-organ expansion apparatus forindwelling a tubular-organ expansion unit in a lumen of a tubular bodyorgan, comprising:a tubular-organ expansion unit including a mesh-likesubstantially tubular body comprising a plurality of woven wires, saidtubular body having a given radial dimension and an outside diameterwhen in an unexpanded state, said woven wires of said tubular bodycomprising a shape memory alloy having a given X-ray contrast, and saidtubular body further being capable of changing the given radialdimension thereof in response to changes in temperature; a catheterincluding:a base portion having an outside diameter; a distal endportion having an outside diameter; an outside portion; a tubular-organexpansion unit attaching portion having a periphery in the vicinity ofthe distal end portion of said catheter for attaching the tubular-organexpansion unit to the catheter; and a catheter sheath having first andsecond open end portions for sheathing said tubular-organ expansion unitwhen said tubular-organ expansion unit is attached to said tubular-organexpansion unit attaching portion of said catheter; and X-ray contrastenhancing means formed on at least a portion of said tubular-organexpansion unit for improving the X-ray contrast of at least a portion ofsaid shape metal alloy relative to said given X-ray contrast.
 9. Atubular-organ expansion apparatus according to claim 8, wherein:saidcatheter is provided with a passageway extending from the base portionthereof to at least a position in the vicinity of the distal end portionthereof; and at least one of side pores and slit-like apertures formedin said catheter for providing communication with said tubular-organexpansion unit-attaching portion of the catheter positioned in thevicinity of the distal end portion of said catheter and providing fluidcommunication between said passageway and the outside portion of saidcatheter.
 10. A tubular-organ expansion apparatus according to claim 9,wherein at least one of the outside diameter of the base portion of thecatheter and the outside diameter of the distal end portion of saidcatheter are larger than the outside diameter of said tubular-organexpansion unit attached to said tubular-organ expansion unit-attachingportion of said catheter when said tubular-organ expansion unit is in anunexpanded state.
 11. A tubular-organ expansion apparatus according toclaim 9, wherein said catheter further comprises:a catheter lumenextending from the base portion of said catheter to at least a positionof the catheter in the vicinity of the distal end portion thereof; and ahollow hub having a hub lumen therein provided on said base portion ofsaid catheter for communicating with said catheter lumen; and saidpassageway being defined at least by said catheter lumen and said hublumen.
 12. A tubular-organ expansion apparatus according to claim 11,wherein said hollow hub comprises:a branch hub having two ports; andwherein a check valve is provided in one of said two ports.
 13. Atubular-organ expansion apparatus according to claim 8, wherein saidcatheter is provided with at least one X-ray non-transmission marker inthe vicinity of the distal end portion thereof.
 14. A tubular-organexpansion apparatus according to claim 13, wherein said catheter sheathincludes at least one of:an X-ray non-transmission material, and said atleast one X-ray non-transmission marker positioned in the vicinity ofthe distal end portion of the catheter.
 15. A tubular-organ expansionapparatus according to claim 8, wherein said catheter sheath comprises:asheath lumen extending between the first and second open end portionthereof; and a hollow hub including a hub lumen provided on the baseportion of the catheter; and a check valve positioned in the hollow hubfor controlling fluid communicating between said sheath lumen and saidhub lumen.
 16. A tubular-organ expansion apparatus for indwelling atubular-organ expansion unit in a lumen of a tubular body organ,comprising:a tubular-organ expansion unit including a substantiallymesh-like tubular body comprising a plurality of woven wires, saidtubular body having a given radial dimension, and an outside diameterwhen in an unexpanded state, said woven wires of said tubular bodycomprising a bidirectional shape memory alloy which is capable ofchanging the given radial dimension thereof in response to a change intemperature; a catheter including:a base portion having an outsidediameter; a distal end portion having an outside diameter; an outsideportion having an outside diameter; a tubular-organ expansion unitattaching portion having an outside diameter and a periphery in thevicinity of the distal end portion of said catheter for attaching thetubular-organ expansion unit to the catheter; and a catheter sheathhaving first and second open end portions and having an inside diameterwhich is no larger than the outside diameter of the tubular-organexpansion unit, when said tubular-organ expansion unit is in theexpanded state; said catheter sheath sheathing said tubular-organexpansion unit when said tubular-organ expansion unit is attached tosaid tubular-organ expansion unit attaching portion of said catheter.17. A tubular-organ expansion apparatus according to claim 16,wherein:said catheter is provided with a passageway extending from thebase portion thereof to at least a position in the vicinity of thedistal end portion thereof; and at least one of pores and slit-likeapertures are formed in said catheter for providing communication withsaid tubular-organ expansion unit attaching portion of the catheterpositioned in the vicinity of the distal end portion of said catheterand for providing fluid communication between said passageway and theoutside portion of said catheter.
 18. A tubular-organ expansionapparatus according to claim 17, wherein said catheter furthercomprises:a catheter lumen extending from the base portion of thecatheter to at least a position of the catheter in the vicinity of thedistal end portion thereof; a hollow hub having a hub lumen thereinprovided on said base portion of said catheter for communicating withsaid catheter lumen; and said passageway being defined at least by saidcatheter lumen and said hub lumen.
 19. A tubular-organ expansionapparatus according to claim 18, wherein said hollow hub furthercomprises:a branch hub having two ports; and a check valve provided inone of said two ports.
 20. A tubular-organ expansion apparatus accordingto claim 16, wherein:both said outside diameter of said catheter and theoutside diameter of said tubular-organ expansion unit attaching portionof the catheter in the vicinity of the distal end portion of saidcatheter are substantially equal in diameter to each other; and whereinboth said outside diameters are at least equal in size to the insidediameter of the tubular-organ expansion unit when said tubular-organexpansion unit is in the unexpanded state so that said tubular-organexpansion unit attaching portion of the catheter is capable of havingsaid tubular-organ expansion unit attached thereto at a temperaturewhich is substantially below body temperature.
 21. A tubular-organexpansion apparatus according to claim 16, wherein at least one of theoutside diameter of the base portion of said catheter and the outsidediameter of the distal end portion of said catheter are larger than theoutside diameter of said tubular-organ expansion unit attached to saidtubular-organ expansion unit attaching portion of said catheter whensaid tubular-organ expansion unit is in the unexpanded state.
 22. Atubular-organ expansion apparatus according to claim 17, wherein saidcatheter is provided with at least one X-ray non-transmission marker inthe vicinity of the distal end portion of said catheter.
 23. Atubular-organ expansion apparatus according to claim 22, wherein saidcatheter sheath includes at least one of:an X-ray non-transmissionmaterial; and said at least one X-ray non-transmission marker positionedin the vicinity of the distal end portion of the catheter.
 24. Atubular-organ expansion apparatus according to claim 16, wherein saidcatheter sheath comprises:a sheath lumen extending between the first andsecond open end portions thereof; and a hollow hub including a hub lumenprovided on the base portion of the catheter; and a check valve ispositioned in the hollow hub for controlling fluid communicating betweensaid sheath lumen and said hub lumen.
 25. A method of medically treatinga lumen of a tubular body organ, comprising:indwelling a tubular-organexpansion unit having a given X-ray contrast into the lumen of thetubular body organ, said tubular-organ expansion unit being definedsubstantially by a shape memory alloy having a cylindrical tubular body,a diameter of said tubular body changing in size in response to a changein temperature; attaching said tubular-organ expansion unit to aperiphery of a unit-attaching portion of a catheter having a distal endportion, said unit attaching portion being positioned in the vicinity ofthe distal end portion of the catheter; sheathing the thus attachedtubular-organ expansion unit and catheter unit attaching portion in acatheter sheath having first and second open end portions; theninserting the thus sheathed tubular organ expansion unit attached to thecatheter into a desired location of the tubular organ, said catheter andsaid tubular-organ expansion unit being projectable out of said cathetersheath; and then expanding the tubular-organ expansion unit with heat ofthe body organ to thereby indwell said tubular-organ expansion unit intosaid desired location; and enhancing the X-ray contrast of at least aportion of said tubular-organ expansion unit relative for said givenX-ray contrast of said tubular-organ expansion unit.
 26. A method formedically treating a lumen of a tubular body organ,comprising:indwelling a tubular-organ expansion unit into the lumen ofthe tubular-body organ, said tubular-organ expansion unit being definedsubstantially by a bidirectional shape memory alloy having a cylindricaltubular body, a diameter of said tubular body changing diametrically insize in response to a change in temperature; attaching saidtubular-organ expansion unit to a periphery of a unit-attaching portionof a catheter having a distal end portion, said unit attaching portionbeing positioned in the vicinity of the distal end portion of thecatheter; forming a sheath of the catheter to have an inside diameterwhich is no longer than an outside diameter of the tubular-organexpansion unit when said tubular-organ expansions unit is in an expandedstate, said catheter sheath having first and second open end portions;sheathing the thus attached tubular-organ expansion unit and the unitattaching portion in the catheter sheath; then inserting the thussheathed tubular-organ expansion unit attached to the catheter through alumen of a guiding catheter previously indwelt in the tubular organ intoa desired location of the tubular organ; projecting said catheter andsaid tubular-organ expansion unit out of said catheter sheath; and thenexpanding the tubular-organ expansion unit with heat of the body organto thereby indwell said tubular-organ expansion unit into said desiredlocation.
 27. A medical treatment method according to claim 26, furthercomprising:inserting the sheathed tubular-body expansion unit into alocation in the body organ where said tubular-organ expansion unit is tobe indwelt; shrinking the size of the tubular-organ expansion unit byfeeding a cool fluid thereto from at least one of said catheter sheathand said catheter in order to shrink the tubular-body expansion unitaround said unit-attaching portion of said catheter, said cool fluidbeing cooler than body temperature; projecting said distal end portionof said catheter with the sheathed tubular-organ expansion unit shrunktherearound out of said catheter sheath; and subsequently drawing thetubular-organ expansion unit, together with said catheter, inside thecatheter sheath.
 28. A method of medically treating a lumen of a tubularbody organ comprising:indwelling a tubular-organ expansion unit having agiven X-ray contrast into the lumen of the tubular-body organ, saidtubular organ expansion unit being defined substantially by a shapememory alloy having a cylindrical tubular body, a diameter of saidtubular body changing in size in response to a change in temperature;attaching said tubular-organ expansion unit to a periphery of aunit-attaching portion of a catheter having a distal end portion, saidunit attaching portion being positioned in the vicinity of the distalend portion of said catheter; sheathing the thus attached tubular-organexpansion unit and catheter unit attaching portion in a catheter sheathhaving first and second open end portions; then inserting the thussheathed tubular-organ expansion unit attached to the catheter through alumen of a guiding catheter previously indwelt in the tubular organ intoa desired location of the tubular organ, said catheter and saidtubular-organ expansion unit being projectable out of said cathetersheath; expanding the tubular-organ expansion unit with heat of the bodyorgan to thereby indwell said tubular-organ expansion unit into saiddesired location; and enhancing the X-ray contrast of at least a portionof said tubular-organ expansion unit relative to said given X-raycontrast of said tubular-organ expansion unit.
 29. A method of medicallytreating a lumen of a tubular body organ comprising:indwelling atubular-organ expansion unit into the lumen of the tubular-body organ,said tubular-organ expansion unit being defined substantially by abidirectional shape memory alloy having a cylindrical tubular body, adiameter of said tubular body changing in size in response to a changein temperature; attaching said tubular-organ expansion unit to aperiphery of a unit-attaching portion of a catheter having a distal endportion, said unit attaching portion being positioned in the vicinity ofthe distal end portion of the catheter; forming a sheath for thecatheter to have an inside diameter which is no larger than an outsidediameter of the tubular-organ expansion unit when said tubular-organexpansion unit is in an expanded state; said catheter sheath havingfirst and second open end portions; sheathing the thus attachedtubular-organ expansion unit and catheter unit attaching portion in thecatheter sheath; then inserting the thus sheathed tubular organexpansion unit attached to the catheter into a desired location of thetubular organ, said catheter and said tubular-organ expansion unit beingprojectable out of said catheter sheath; and then expanding thetubular-organ expansion unit with heat of the body organ to therebyindwell said tubular-organ expansion unit into said desired location.30. The medical treatment method according to claim 29, wherein:afterthe combination of said catheter and said catheter sheath is insertedthrough the lumen of a guiding catheter previously indwelt in thetubular organ, into a location where said tubular-organ expansion unitis to be indwelt, the distal end portion of said catheter with thetubular-organ expansion unit attached thereto is projected out of saidcatheter sheath; then reducing the size of said tubular-organ expansionunit by feeding a cool fluid from at least one of said catheter sheathand said catheter in order to shrink said tubular-organ expansion unitaround the unit-attaching portion of said catheter, said cool fluidbeing cooler than body temperature; and then withdrawing saidtubular-organ expansion unit, together with said catheter, inside thecatheter sheath.